1. Field of the Invention
The present invention applies to radio communications systems in which several remote terminals communicate voice or data with a base station and, in particular, to such a system in which the base stations uses a broadcast channel that is also used to transmit voice or date to specific remote terminals.
2. Description of the Prior Art
Mobile radio communications systems such as cellular voice radio systems typically have a base station available for use by mobile remote terminals, such as cellular telephones or wireless web devices. The base station typically transmits a broadcast channel (BCH). The BCH is broadcast to all remote terminals whether they are registered on the network or not and informs the remote terminals about the network. In order to access the network, a remote terminal must normally tune to and listen to the BCH before accessing the network. A remote terminal will typically scan a range of likely frequencies when it wants to access the network until it finds the strongest BCH. It will then use the information transmitted or broadcast in the BCH to access the network.
The BCH typically carries as much data as a typical traffic channel. However, because it is necessary in order to permit remote terminals to access the network, the BCH is reserved exclusively for broadcast network data.
The present invention allows the broadcast channel to be used, in part, for carrying traffic. This allows less of the channel resources to be dedicated to the broadcast channel and more of the channel resources to be dedicated to traffic. In one embodiment, traffic is transmitted during a significant portion of the broadcast channel. When a broadcast burst supercedes traffic messages, the superceded traffic message is transmitted in the next traffic channel slot.
In one embodiment, the present invention comprises broadcasting a broadcast burst in a broadcast channel from a base station. The broadcast channel has at least one assigned frequency and a plurality of time slots, at least one time slot being assigned for the broadcast burst. The invention further comprises transmitting traffic in a traffic channel from the base station. The traffic channel has a timed frequency hopping scheme, the hopped frequencies including the at least one broadcast channel frequency so that the traffic channel collides with the broadcast burst time slot. The invention further comprises broadcasting the broadcast burst in the traffic channel from the base station when the traffic channel collides with the broadcast channel, receiving a request for retransmission of traffic after the broadcast burst is broadcasted in the traffic channel due to a collision, and retransmitting the traffic in the traffic channel in response to the retransmission request.